The Field of the Invention
The present invention relates to the manufacture of semiconductor devices, and particularly to the removal of damage or contamination, especially oxide containing contamination, from a semiconductor substrate, and the growth of extremely high quality oxide films during the manufacture of a semiconductor device. More particularly, the present invention is directed to improved methods for removing contamination and damage a substrate, and for growing contamination- and defect-free oxide films on a substrate, by in situ rapid thermal etch and rapid thermal oxidation.
The Relevant Technology
Many of the steps performed in the manufacture of semiconductor devices require that contamination or damage be removed from a silicon substrate. The various processes typically used to remove contamination or damage generally may be classed as wet cleaning methods or dry cleaning methods. Wet cleaning of various types can introduce many types of contamination. Placing the substrate in contact with liquids tends to result in particulate contamination of the substrate. Dry cleaning methods employing plasma energy or similar energy sources can substantially avoid causing particulate contamination, but can cause lattice damage to the substrate. Dry cleaning methods without plasma or similar energy sources to assist the cleaning processes can avoid damage to the substrate, but are typically too slow for cost-effective manufacturing.
Deposition of extremely high-quality oxide films is also generally required in the manufacture of semiconductor devices, such as in deposition of gate oxides in state of the art field-effect transistors. Production of such extremely-high quality oxide films requires that the substrate be contamination-free and damage-free.
Effective, high-throughput cleaning methods resulting in a contamination-free and damage-free substrate are thus needed.
An object of the present invention is to provide improved methods for removal of contamination and damage of a substrate.
Another object of the present invention is to provide methods for removal of contamination and damage of a substrate, which methods provide increased throughput through the performance of multiple process steps in situ.
Yet another object of the present invention is to provide methods for removal of contamination and damage of a substrate, which methods include growing an extremely high-quality oxide film in situ after removal of said contamination and damage.
Still another object of the present invention is to provide methods for removal of contamination and silicon damage of a substrate due to stress from plasma etching or stress in the area of a field isolation region such as a LOCOS region, which methods may be readily performed by current processing equipment with little or no modification thereof
In accordance with the present invention, at least both a rapid thermal etch step and a rapid thermal oxidation step are performed on a semiconductor substrate in situ in a rapid thermal processor. Various combinations of etch steps and oxidation steps may be employed for various purposes. A method including an oxidation step followed by an etch step may be used to remove contamination and damage from a substrate. A method including a first etch step, followed by an oxidation step and a second etch step, may likewise be used to remove contamination and damage, and a final oxidation step may optionally be included to grow an oxide film. A method including an etch step followed by an oxidation step may also be used to grow an oxide film. The performance of the various steps in situ in a rapid thermal processor improves throughput and reduces the opportunity for contamination. The elevated temperatures in the rapid thermal processor environment increase the reaction rates for the etch step without causing radiation damage to the substrate. The extremely short ramp up times and processing times of the rapid thermal processor keep diffusion effects quite small preventing unwanted migration of dopants and impurities. These methods result in an extremely clean, damage-free substrate.
These and other objects and features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.